Method of making a primer insert for use in polymer ammunition

Abstract

One embodiment of the present invention provides a polymeric ammunition cartridge and methods of making and using the same. The cartridge includes a substantially cylindrical insert connected to a substantially cylindrical polymeric middle body. The substantially cylindrical insert includes a top surface opposite a bottom surface and a substantially cylindrical coupling element that extends from the bottom surface, a primer recess in the top surface that extends toward the bottom surface, a primer flash hole positioned in the primer recess to extend through the bottom surface, and a flange that extends circumferentially about an outer edge of the top surface. The substantially cylindrical polymeric middle body includes a substantially cylindrical polymeric bullet-end and a substantially cylindrical polymeric coupling end connected by a powder chamber, wherein the substantially cylindrical polymeric coupling end extends over the substantially cylindrical coupling element and covers a circumferential surface of the primer flash hole.

What is claimed is: 
     
       1. A method of making a metal primer insert for a polymeric ammunition cartridge comprising the steps of:
 providing an insert blank for machining; 
 machining a top surface on the insert blank; 
 machining a flange that extends circumferentially about an outer edge of the top surface; 
 machining an outer channel adjacent to the flange that extends circumferentially about the insert blank, wherein the outer channel is adapted to receive a polymer overmolding; 
 machining a substantially cylindrical coupling element that extends from the outer channel to a coupling tip, wherein the substantially cylindrical coupling element includes an inner coupling element surface that extends from the coupling tip to a bottom surface, wherein the bottom surface is opposite the top surface, wherein the substantially cylindrical coupling element is adapted to receive the polymer overmolding; 
 machining a primer recess in the top surface that extends toward the bottom surface; 
 machining a primer flash aperture in the primer recess through the bottom surface; and 
 machining a groove in the primer recess around the primer flash aperture adapted to receive the polymer overmolding. 
 
     
     
       2. The method of  claim 1 , wherein the primer flash aperture is larger than a flash hole in a metal ammunition cartridge of the same caliber. 
     
     
       3. The method of  claim 1 , wherein the primer flash aperture is larger than a flash hole in a metal ammunition cartridge of the same caliber to allow polymer overmolding into the primer flash aperture. 
     
     
       4. The method of  claim 1 , wherein the metal primer insert is a 5.56 mm, 7.62 mm, .223, 308, 338, 3030, 3006, and .50 caliber primer insert. 
     
     
       5. The method of  claim 1 , wherein the metal primer insert is a 380 caliber, 38 caliber, 9 mm, 10 mm, 20 mm, 25 mm, 30 mm, 40 mm, 45 caliber and the like. 
     
     
       6. The method of  claim 1 , wherein the insert blank is a metal, an alloy, or a ceramic alloy. 
     
     
       7. The method of  claim 1 , wherein the insert blank is stainless steel or brass. 
     
     
       8. The method of  claim 1 , wherein the insert blank is a 102, 174, 201, 202, 300, 302, 303, 304, 308, 309, 316, 316L, 316Ti, 321, 405, 408, 409, 410, 415, 416, 416R, 420, 430, 439, 440, 446 or 601-665 grade stainless steel. 
     
     
       9. The method of  claim 1 , wherein the insert blank is a Ti6Al4V.